Controlled tension rolling in tandem cold mills



Sept. 22, 1936. HUDSON 2,054,820

CONTROLLED TENSION ROLLING IN TANDEM COLD MILLS Filed Jan. 18, 1935 4 Sheets-Sheet 1 gma/V M Sept. 22, 1936. E. B. HUDSON 72,054,820 7 CONTROLLED TENSION ROLEING IN TANDEM COLD MILLS Filed Jan. 18, 1955 4 Sheets-Sheet 2 I 6% & 8 a a fi D Q Q Q Q v INVENTOR ATTORN EY! Sept. 22, 1936. E. B. HUDSON 2,054,320

CONTROLLED TENSION ROLLING IN TANDEM COLD MILLS Filed Jan. 18, 1935 4 Sheets-Sheet6,

INVENTOR Ella/baa ATTORNEY$ Sept. 22,1936. 2,054,820

CONTROLLED TENSION ROLLING IN TANDEM COLD MILLS E. B. HUDSON 4 Sheets-Sheet 4 Filed Jan. 18, 1955 INVENTOR,

W V M ATTORNEY$ Patented Sept. 22, 1936 UNITED STATES PATENT OFFICE CONTROLLED TENSION ROLLING IN TANDEM COLD MILLS Application January 18, 1935, Serial No. 2,402

19 Claims.

My invention relates to an improved method of cold rolling a metal strip, by the use of several mills arranged in tandem, the number of the mills being determined by the desired amount of gauge reduction, so that the rolling operation may be completed by a single uni-directional pass through the train.

I have pointed out in various copending applications in my name that successful continuous cold rolling under tension involves the necessity of continuously maintaining constant predetermined tensions with respect to each pass, in spite of variations in elongation which may sporadically occur due to various causes. In the tandem train of mills there must likewise be a nice proportionment of the speeds of the various dynamic instrumentalities, in addition to the tension control. It is, an object of my present invention to accomplish these ends in a mechanism which will 20 be elastic both in set up and in its operation. It

is an object of my invention to simplify and thereby cheapen the combination of apparatus required for any given series of rolling operations. It is an object of my invention to provide a con- 25 tinuous band of metal for the rolling operation by a new procedure which is quite flexible, but which nevertheless eliminates ends of the strips to be threaded manually, while providing a rolling operation free of end wastage. It is an object of my invention to eliminate a number of space-consuming instrumentalities hitherto thought necessary in the formation of a continuous supply of rolling material. It is an object of my invention to provide a more flexible control and regulation of the tension distribution at each pass.

These and other objects of my invention which will be set forth hereinafter, or will be apparent to one skilled in the art upon reading these specifications, I accomplish by that certain construction and arrangement of parts and by that process of which I shall hereinafter set forth a purely exemplary embodiment, it being understood that my invention is not limited thereto.

For the sake of clearness, reference is now made to the drawings, wherein Figure 1 shows diagrammatically an assemblage of a three mill train complete with auxiliary equipment for controlling speed and tension.

Fig. 2 is a diagrammatic lay-out in plan showing the mills and other devices in the train, together with the drives therefor.

Fig. 3 is a pass tension diagram typical of tension controls which may be had with my apparatus, but not in any sense limiting, inasmuch as the tension components at each pass may be regulated as desired, as I shall hereinafter explain.

Fig. 4 is a view partly in elevation and partly in section of an adjustable accumulator for effecting tension control. 6

Fig. 5 is an elevational view, with parts in section, of the non-return clamp mechanism which forms a part of my assembly.

Fig. 6 is an end elevational view of the clamp.

Fig. 7 shows in plan the combination booster 10 and static tension means which I- prefer to employ.

Fig. 8 is an elevational view, with portions in section, of the combination booster and static tension control device.

My present invention does not contemplate that the rolling operation be continuous. It is intermittent in the sense that the rolling interval is based on the length of the built-up coils and the entering speed of the strip into the first mill. The maximum weight of the built-up coils will be determined by the largest size of coil that can be handled practicably.

It will be understood that coils as delivered from the hot mill are relatively limited in length, varying with the weight of the slab used, say, from 180 feet to 300 feet. The hot rolled strip sheet may be pickled in a continuous pickler to remove all scale.

To attempt to take coils of this length and weld them together at the cold mill train involves the problem of providing looping facilities, if the mill is to be kept running constantly; and these looping facilities take up a relatively very large amount of space. particularly desirable to shut down the mill train every time a coil of ordinary length is to be welded to the supply in process of rolling. Consequently, I desire to start at the tandem mill train with coils 'of greater than normal length. 40 This increases the rolling intervals and decreases the time of shut down for welding, since for a given length of strip fewer welds need be made at the mill. Consequently, I prefer to provide large coils containing strip sheet material, at least, say, 1000 feet long, and as much longer as may be conveniently handled, depending some- I what upon the starting gauge of the metal. These large coils may be provided by previous welding operations, and these operations may be 5 carried ont either prior to the continuous pickling, or subsequent thereto, as desired, without interfering with the rolling operation. In the practice of my invention, therefore, I provide, preferably adjacent thecontinuous pickler, an electric On the other hand, it is not 35' butt welding device, a flash cutter and coiling means for building up these jumbo coils.

In the mill train I provide in the order named, a decoiler, a shear for trueing up the edges of the strips to be joined, an electric butt welder and a flash cutter, all ahead of the first stand of mills. Since with these jumbo coils it is practicable to stop the mills when a. new coil has to be attached, no looping device at the entering side of the mill need be provided. A brake to exert back tension on the first stand of rolls may be provided ahead of the first stand and, if desired, a static tension regulator may be placed between this brake and the first stand; although this is not usually necessary. The mill train proper consists of as many stands of rolls as may be desired. Preferably between adjacent stands there will be pulling devices which, together with the mills themselves and a final pulling device or coiler, constitute what I shall hereinafter refer to as the dynamic instrumentalities in the train, since they have to do with the travel of the sheet. Between each of these dynamic instrumentalities and each adjacent dynamic instrumentality, I provide a static tension control device, preferably adjustable, as I shall hereinafter describe. The static tension control device serves to maintain the tension continually at a constant, predetermined value in spite of any variations in the elongation of the strip; but where variations in the elongation do occur they may be employed, as hereinafter described, to control the speeds of succeeding or preceding dynamic instrumentalities. The final pulling device in the train may conveniently be a device of the tight coiler type, inasmuch as when the mechanism is stopped for the welding of a new coil to the end of the strip, advantage may be taken of this stoppage to remove a rolled coil from the opposite end of the. rolled strip. Regarding the final coiler as a dynamic instrumentality, it will be remembered that there is located between this instrumentality and the adjacent mill, one of the static tension control devices. Consequently, when the mill train is stopped for the removal of a rolled coil, and the rolled strip? sheet is severed intermediate the coiler and the final mill, some means must be provided to prevent return travel of the strip into the last static tension control device. I provide this means in the form of a non-retum clamp, which I shall hereinafter more particularly describe. No looping instrumentality in the ordinary sense of the word at the exit side of the mill is required, and it is only necessary to leave suflicient unsevered strip, beyond the non-return clamp, to permit the attachment of the end thereof to the coiler drum for the removal of the finished coil therefrom. It will be usual to provide a shear between the non-return clamp and the final coiler.

I shall now more particularly describe my apparatus, the general lay-out of which will be apparent from Figs. 1 and 2. I have shown an assembly of apparatus suitable for the cold rolling of strip of sheet width. This strip is designated at I. My invention contemplates the rolling of it in the direction of the arrow 2, through a tandem mill train, which in the embodiment shown comprises three stands of four high mills, each stand having relatively small working rolls, and relatively large backing up rolls. A jumbo coil indicated at 3 maybe placed in the decoiler 5. The ends of the coil and of the strip I maybe sheared true by the shear 8. These ends are then welded together by the instrumentality indicated diagrammatically at 9, which may be a welder of known type for producing a butt weld joining the ends of strip sheet material. So that this weld may subsequently be rolled, any flash, or excess of metal thereat, may be removed by a flash cutter of known type indicated at H). The strips pass through mills A, B and C in the train. combination pulling devices and static tension regulators which I shall hereinafter refer to by the term booster regulators. These devices are indicated at D. Beyond the last mill C, there is located a static tension device E. Prior to its entry into the first mill, the strip may pass around a pair of braking rolls ll, one of which is attached to a brake drum 12 mounted in a suitable :framework, so as to exert some back tension on the strip as it enters the mill A. Beyond the static tension device E, there is located a non-return clamp G. A pit 39 accepts a small loop I of the strip after it passes the clamp G, to permit attachment of the end of the loop after it is sheared by the shear I3, to the coiler drum. A finished coil is indicated at 4, which may be removed from the coiler drum l4 after the shearing operation.

The mills A, B and C, are driven respectively by motors I5, l5 and IS". The boosters D are driven respectively by the motors I8 and I8. The final dynamic instrumentality, namely the coiler I4, is driven by a motor 2|. The motors l5, etc. drive the mills through reduction gears l6 and pin'ions IT. The motors 18, etc. drive the boosters through gear reduction trains l9. and pinion stands indicated at 20. The motor 2| drives the coiler drum l4 through a gear reduction device 22, the shaft 23 thereof being equipped with a splined connection 24 to permit the disengagement of the coiler drum. Power may be supplied to the various motors from electrical power leads indicated at 25. Where it is desired to control the overall speed of the train by controlling the speed of the motor of the first mill, a hand rheostat 26, for the motor l5, may be provided. The first static tension control device following the mills A and B may be caused to control the speeds of the booster motors l8 and 18', respectively, through rheostats indicated at 21. The static tension control devices which follow each booster may be caused to control the speeds of the motors l5 and I5" of the succeeding mills B andCjrespectively, through rheostats 29. The final static tension control device E may be caused to control the speed of the coiler motor 2| through the rheostat 3|. Where over-all control of the mill train is desired from the coiler end rather than from the entering-end of the train, the various static tension control devices may be caused to control the speeds of preceding mills, or other dynamic instrumentallties, by coupling them up with preceding rheostats shown in the circuit diagram portion of Fig. l, as will be readily understood.

Each of the static tension control devices comprises a pair, of knee rolls and a movable breast roll adapted to take up the strip in a parallel sided loop over the knee rolls. The breast roll is urged away from the knee rolls under a constant force for any given adjustment of the mills, and therefore serves to maintain the tension on the strip continuously at the contant, predetermined value. Variations in elongation of the strip, however, are taken up by movements of the breast roll, and therefore the breast roll can Between these mills are positioned the be mechanically coupled up with the appropriate rheostat to change the rheostat setting by reason of its movements. Preferably there will be a normal zone of movement of the breast roll, in which no rheostat control is effected. It will be obvious that the rheostats may be coupled up to the static tension control devices in a variety of ways. One such way is fully disclosed in my copending application entitled Rolling under tension Ser. No. 668,100 filed April 26, 1933, and reference is made thereto for a fuller disclosure of one operative coupling, it being understood that my invention is not restricted thereto.

In the preferred form of my invention, the breast rolls have a constant force applied to them by being connected to hydraulic cylinders which may be actuated by any pressure fluid. Preferably the fluid will be a non-compressible one, such as water or oil, and I have shown each of the static tension devices connected by means of a suitable conduit to adjustable accumulators, which I shall hereinafter more particularly describe, but which are shown in Fig. 1 at F, F, etc.

Fig. 3 shows a typical tension diagram, the tension in pounds per inch of width of the strip being indicated by appropriate figures, and the positions of the various dynamic instrumentalities being indicated by the letters which indicate these instrumentalities in Figs. 1 and 2. The line representative of the tension in the strip as it enters and leaves each dynamic instrumentality is the line H.

The booster regulator devices are shown in Figs. 7 and 8, in a form which is preferred by me. The booster proper comprises three driven rolls 51, 58, and 59 in pyramid formation. These rolls may be connected to the pinion stands 20, by means of couplings 62, 63 and 64. The rolls 51 and 59 also form knee rolls for the tension regulators, of which there are two, one on each side of the booster proper. The static tension regulators therefore comprise respectively, knee rolls 55 and 51 with the breast roll 58, and knee rolls 59 and 6|, with the breast roll 80. The

-- breast rolls of these static tension regulators therefore serve to wrap the strip I more tightly about the rolls 51, 58 and 59, which form the booster. The apparatus has a framework 69, mounted upon suitable supports 10. The rolls 55, 51, 58, 59 and GI are journaled in this framework so as to be rotatable, but not otherwise movable. The rolls 55 and BI will preferably not be driven. The rolls 56 and 60 have their bearings in housings which are slidable in guideways 88 in the frame member 69. Yokes 65 connect these housings, and are acted upon by plungers 88 operating in hydraulic cylinders 61. It has previously been explained how these cylinders are connected to appropriate accumulatars, so that the efiect of the pressure therein is to urge the pistons 68 upwardly, likewise urging the rolls 56 and 80 upwardly, so that the strip I is taken up over the knee rolls in parallel sided loops as shown. The force on the cylinders 61 being constant, though not usually equal, will continuously control the tensions on the strip as it enters and as it leaves the machine of Figure 8, to constant, predetermined values. Where variations of elongation occur in the strip, the rolls 56 and 80 will move upwardly or downwardly to take care of these elongations; and it has already been explained how these movements are caused to control rheostats for the various dynamic instrumentalities. The driving of the rolls 51, 58 and 59 has the effect of pulling the strip, and therefore, when the static tension regulators are under proper pressures, of effecting a higher tension on the strip l as it enters the booster regulator than the tension thereon as it leaves it, which is the reverse of that condition desired on the mills. It may be said that in ordinary tension rolling operations, a positive differential of tension is desired, namely, a tension which is greater on the exit side of the mill than on the entering side. This can be maintained in a tandem train of mills without intermediate pullers if the tension is arranged to be cumulative at each pass; but in such a system the tension increases as the gauge of the strip decreases, which is sometimes undesirable. With booster regulators between mills, a positive tension differential may be maintained at each pass without cumulative tension, or even with the reverse of it, as will be readily understood.

The top of the booster regulator frame may be finished by a tie member indicated at H in Fig. 8.

In Fig. 4, I have indicated a type of adjustable accumulator similar to that set forth in my copending application entitled Reversible rolling under controlled tension Ser. No. 31,346 filed July 15th, 1935. This accumulator comprises a frame member 45, and a bearing member 44 mounted thereon. A hydraulic cylinder 33 is mounted by means of trunnions 34 in the bearings 44 for rotative movement. There is a piston 38 in the cylinder 33 connected by means of a link 39 to a yoke 40. Rods 4| may be attached to the yoke 40 at one end, and to another yoke member 46 at the other, and these rods are mounted for longitudinal movement against rollers 42, attached to the cylinder 33. Weights 43 may be attached to these rods, and may be adjustable. A gear wheel or portion thereof 31 may be attached to one of the cylinder trunnions, and may mesh with a pinion 38 on a reversible motor 35. Connection to the interior of the cylinder may be made through a connection 48, communicating with a passageway in one of the trunnions 34.

Regarding this device as an accumulator, the cylinder 33 being partially filled with fluid, it will be noted that the greatest effect of the weights 43 upon the piston 38 will be had when the cylinder is in upright or vertical position as shown. If the cylinder is tilted to the horizontal position, as indicated by the line 41, the weights 43 will have no substantial effect upon the piston 38. By choosing intermediate positions between the vertical and horizontal, one of which positions is indicated by the lines 48, it will be clear that the effective pressure in the accumulator may be varied as desired, from zero to a maximum determined by the weights 43. It has hereinabove been explained how accumulators such as that shown in Fig. 4 are connected respectively with the cylinders 61 of the booster regulators. In the connections therebetween there may, of course, be appropriate means for letting fluid out of the various systems, or pumping more fluid thereinto. With a given pressure in the system, the positions of the rolls 56 and 58 may be varied, if permitted by the strip, by variation of the volume of fluid in the said pressure system.

The non-return clamp is illustrated in Figs. 5 and 6 and comprises a housing 49, and strip engaging shoes 50 connected by means of toggle links 5| to pivots 52 on the housing. The length of the links 5| is such that the shoes 50 will be pressed tightly together as these links approach dead center, and so that the links cannot pass dead center. For the positive actuation of the clamp shoes, I prefer to provide pressure cylinders SI and pistons 53' therein, which are connectedwith the toggle links 5|. In some operations, the-positive actuation of the non-return clamp may not be necessary, inasmuch as the arrangement is such that the strip I can pass the clamp in the direction indicated by the arrow 2 but cannot return; and it may therefore be sufficient merely to cause the shoes to be pressed lightly against the strip at all times. However, for most operations it will be preferable to bring the shoes out of contact with the strip entirely when the strip is moving, so as to avoid frictional effects and a possible marring of the cold rolled surface of the strip. Consequently, I have indicated' fluid connections to the cylinders 54 upon both sides of the pistons therein.

Hereinabove I have described an exemplary embodiment of my invention showing essential features thereof. It will be understood, however, that modifications may be made not only in the general assembly, but also in the specific apparatus which goes to make up the general assembly. The number of mills, for example, may

be increased or diminished, or the type of mills may be changed. Individual static tension regulators and individual intermediate pullers may likewise be provided, etc. It will be understood that my invention is not limited otherwise than specifically set forth in the appended claims; and having thus described my invention in an exemplary embodiment, what I claim as new and desire to secure by Letters Patent, is:-

1. In combination, a decoiler; a welder, a pinrality of tandem mills and a final coiler, a combination of two static tension controlling devices and a booster device located between each mill and each adjacent mill, and a static tension controlling device located between the flnal mill and said coiler.

2. A process of rolling strip metal, which comprises decoiling a coil thereof and rolling said coil through a tandem train comprising a plurality of mills, controlling the tension on the strip as it enters and as it leaves each pass to a-predetermined, constant value continuously, stopping said mill train prior to the passage of all of said strip therethrough, severing a useful portion of rolled strip at the exit side of said mill, and welding a portion of unrolled strip at the entering side of said mill.

3. In combination, a decoiler, a welder, a mill and a final coiler, a static tension device located between said mill and said coiler, and a nonreturn clamp located between said device and said coiler.

4. In combination, a decoiler, a welder, a plurality-of mills and a final coiler, static tension regulating. devices located between each mill and each adjacent mill and between the final mill and said coiler, and a non-return clamp located between the final static tension regulator and said coiler.

5. In combination, a decoiler, a welder, a plurality of mills forming a tandem train, a combination static tension regulator and tension booster located between each mill and each adjacent mill, a final coiler, a static tension regulator located between the final mill and said coiler, and a nonreturn clamp located between the final static tension regulator and said coiler.

6. A process of rolling strip metal which comprises decoiling a coil thereof, rolling said coil under tension througha tandem trainof mills while maintaining continuously a constant, predetermined tension at each pass, coiling a rolled portion of said strip, stopping said mill, holding a portion of said strip beyond said final mill against return travel, severing said strip therebeyond, removing the rolled portion, and welding an additional length of strip to an unrolled portion of said first mentioned strip.

7. A process of rolling strip metal which comprises decoiling a coil thereof, rolling said coil under tension through a tandem train of mills while maintaining continuously a constant, predetermined tension at each pass, coiling a rolled portion of said strip, stopping said mill, holding a portion of said strip beyond said final mill against return travel, severing said strip therebeyond, removing the rolled portion, and welding an additional length of strip to an unrolled portion of said first mentioned strip, releasing said clamping means and continuing the rolling operation.

8. A process of rolling strip metal, which comprises hot rolling slabs to form strip sheets, forming pickled coils of said strip sheets of greater length than the normal strip sheet length, rolling a coil under controlled constant tension'in one direction nearly to an end thereof, stopping the rolling operation, severing a useful length of said rolled strip and simultaneously attaching to the unrolled end thereof another of said coils.

9. A booster regulator device comprising a housing, a plurality of driven rolls journaled therein and arranged for the sinuous passage of a strip about a large arc of the surface of each roll, a pair of idler rolls, said idler rolls adapted to co-operate with a pair of said first mentioned rolls as knee rolls for static tension regulation, and a pair of movable rolls adapted to take up said strip in parallel sided loops over said knee rolls, and means for exerting a constant force on said movable rolls to urge said movable rolls away from said knee rolls..

10. A booster regulator device comprising a housing, a plurality of driven rolls journaled therein and arranged for the sinuous passage of a strip about a large arc of the surface of each roll, a pair of idler rolls, said idler rolls adapted to co-operate with a pair of said first mentioned rolls as knee rolls for static tension regulation, and a pair of movable rolls adapted to take up said strip in parallel side'cl loops over said knee rolls, and means for exerting a constant force on said movable rolls to urge said movable rolls away from said knee rolls, said means comprising hydraulic cylinders and operative connections between said cylinders and said movable rolls.

11. A non-return clamp comprising a housing having an opening for the passage of a strip, a

pair of clamping shoes in said housing for contactingopposite sides of said strip, and toggle connections between said shoes and said housing, said toggle connections serving to bring said shoes against said strip from opposite sides without passing dead center. I

12. A non-return clamp comprising a housing having an opening for the passage of a strip, a pair of clamping shoes in said housing for contacting opposite sides of said strip, toggle connections between said shoes and said housing, said toggle connections serving to bring said shoes against said strip from opposite sides without passing dead center, and power means for actuating said toggles.

13. In combination, a decoiler, a welder, a plurality of mills and a final puller, said mills and said puller constituting dynamic instrumentalities, at least one static tension regulator located between each of said dynamic instrumentalities and each adjacent dynamic instrumentality, said static tension regulating devices each comprising a pair of knee rolls and a movable breast roll, together with a fluid pressure cylinder for actuating said breast roll, a plurality of tilting, fluid pressure accumulators, and connections between said accumulators respectively and said fluid pres sure cylinders.

14. The combination of claim 13, in which a pulling device is located between each of said mills and each adjacent mill.

15. In combination, a decoiler, a welder, a plurality of mills, intermediate pullers and a final puller, said mills and said pullers constituting dynamic instrumentalities, at least one static tension regulator located between each of said dynamic instrumentalities and each adjacent dynamic instrumentality, said static tension regulating devices each comprising a pair of knee rolls and a movable breast roll, together with a fluid pressure cylinder for actuating said breast roll, a plurality of tilting, fluid pressure accumulators, and connections between said accumulators respectively and said fluid pressure cylinders, said intermediate pullers being located between each of said mills and each adjacent mill.

16. The combination of claim 15, wherein a braking device is located preceding the first mill in said train.

17. An intermittent tension rolling tandem train assembly comprising a decoiler, means for joining strip from said decoiler with preceding strip already in the mills, a plurality of mills forming a tandem train for rolling said strip and at least one pulling device for operating on said joined strip to exert tension thereon, said mills and said pulling device constituting dynamic instrumentalities in said train, a static tension regulating device located between each dynamic instrumentality and each succeeding dynamic instrumentality, and means for holding the strip under tension and means for severing the strip therebeyond, both of said means preceding the final dynamic instrumentality, whereby upon stoppage of the mill train a supply of rolled metal may be severed and removed from said pulling device without relieving tension on the material remaining in the mills.

18. The combination set forth in claim 17, in which there is a braking device prior to the first dynamic instrumentality in said train.

19. The combination set forth in claim 1'7, in which each static tension regulator device is connected with a speed control device for an adjacent dynamic instrumentality.

EDWIN B. HUDSON. 

